When Fairfax County officials set out three years ago to bring running water and indoor bathrooms to the Chapel Acres community in south-central Fairfax County, they hoped the plan would bring some measure of suburban affluence to this impoverished neighborhood of 50 families.

The project was successful--in fact, it was too successful.

Along with the new indoor toilets and new water faucets, the residents received something else: new property tax bills they can't afford to pay.

Within a year after the county modernized the homes, property tax bills shot up 89.3 percent, county records show. Now the county is being asked to help the low-income families in Chapel Acres pay those higher tax bills.

"We're getting ourselves in the posture of creating high-priced houses for those who can't afford to live in them," Supervisors Chairman John F. Herrity said Monday during a heated debate over how to untangle the community's predicament.

"We're not talking about mansions," said Supervisor Marie B. Travesky (R-Springfield). "These are people who can't afford that kind of an increase."

County records show the drastic increases in property values between 1980 and 1981: One house valued at $1,700 before the improvements jumped to $15,000, tacking $195 onto the owner's tax bill. Another escalated from $19,625 to $42,500, resulting in a $336 tax hike.

The county Department of Human Services has asked the supervisors to spend $9,974 over the next three years to subsidize the tax payments and cushion the low-income residents against the increases. However, a sharply divided board decided to see how many more communities might qualify for assistance before they decide whether to help Chapel Acres.

"This would be setting the worst kind of precedent possible," said Supervisor Thomas M. Davis III (R-Mason). "You're asking (some taxpayers) to pay the bills for these others."

"What we're contemplating is a whole new welfare program," charged Herrity.

Under the county staff's proposal, the assistance program would pay a percentage of the increased property taxes for qualified homeowners, based on their income.

The county spent $1.2 million to install sewer lines, water lines and recreational facilities in the 32-year-old subdivision, a small enclave ringed by new developments of large, expensive homes.

Travesky argued that the new subdivisions with their increasing property values have had just as strong an impact as the new sewer and water facilities in Chapel Acres. She said many Chapel Acres families may be forced out of their homes if the county doesn't help them with the tax bills.

"We have to draw a line as to how far the government's going to go," shot back Davis.